Engine Oil Compositions with Improved Fuel Economy Performance

ABSTRACT

An engine lubricating oil exhibiting a fuel economy improvement is disclosed. The engine oil composition meets at least one of ILSAC GF-4, API CI-4, API CJ4, ACEA A1, ACEA A5, ACEA B1, ACEA B5, ACEA C1, ACEA C2, ACEA C3, ACEA C4A, and JASO DL-1 performance specifications. The composition comprises at least an isomerized base oil comprising a consecutive number of carbon atoms and having a CCS Viscosity at −35° C. of less than or equal to 7000 mPa, a T 95 -T 5  boiling range distribution of less than or equal to 200° C., a ratio of weight percent molecules with monocycloparaffinic functionality to weight percent molecules with multicycloparaffinic functionality of greater than 15, and an Oxidator BN of greater than 30 hours; and 0.05 to 40 wt %. of at least an additive selected from the group of metal detergents, dispersants, wear inhibitors, anti-oxidants, friction modifiers, viscosity modifiers, corrosion inhibitors, seal swelling agents, metal deactivators, anti-foamants, and mixtures thereof.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit under 35 USC 119 of ProvisionalApplication 60/991296 filed Nov. 30, 2007. This application claimspriority to and benefits from the foregoing, the disclosure of which isincorporated herein by reference.

FIELD OF THE INVENTION

The invention relates generally to engine oil compositions. In oneembodiment, engine oil compositions with improved fuel economy.

BACKGROUND

US government mandated standards for fuel economy and emissions haveplaced increasing demands on passenger car manufacturers. This in turnhas resulted in automobile manufacturers requesting high quality engineoils used for passenger car motor oils (PCMOs).

Starting in 1995, automakers requested higher quality engine oils tohelp meet stringent federally mandated passenger car fuel economy andemissions standards. The International Lubricant Standardization andApproval Committee (ILSAC), working with API, ASTM, and SAE previouslyproposed a GF-3 Minimum Performance Standards for Passenger Car MotorOils (PCMO) with significantly improved fuel economy and volatilityrequirements compared to previous GF-1 and GF-2 PCMO standards. InJanuary 2004, ILSAC issued its latest Minimum Performance Standard forEngine Oils, ILSAC GF-4. Besides improved fuel efficiency, GF-4requirements include improved oxidation resistance, improvedhigh-temperature deposit control, better cam and lifter weardiscrimination, improved low temperature wear protection, and improvedlow temperature used oil pumpability. ILSAC GF-4 oils also have reducedphosphorous and sulphur contents to provide enhanced emission systemprotection.

During the last five years, the petroleum industry has invested to makethe higher viscosity index (VI) basestocks necessary to help meet thesenew engine oil requirements. In a number of patent publications andapplications, i.e., US 2006/0289337, US2006/0201851, US2006/0016721,US2006/0016724, US2006/0076267, US2006/020185, US2006/013210,US2005/0241990, US2005/0077208, US2005/0139513, US2005/0139514,US2005/0133409, US2005/0133407, US2005/0261147, US2005/0261146,US2005/0261145, US2004/0159582, U.S. Pat. No. 7,018,525, U.S. Pat. No.7,083,713, U.S. application Ser. Nos. 11/400570, 11/535165 and11/613936, which are incorporated herein by reference, a Fischer Tropschbase oil is produced from a process in which the feed is a waxy feedrecovered from a Fischer-Tropsch synthesis. The process comprises acomplete or partial hydroisomerization dewaxing step, using adual-functional catalyst or a catalyst that can isomerize paraffinsselectively. Hydroisomerization dewaxing is achieved by contacting thewaxy feed with a hydroisomerization catalyst in an isomerization zoneunder hydroisomerizing conditions. The Fischer-Tropsch synthesisproducts can be obtained by well-known processes such as, for example,the commercial SASOL® Slurry Phase Fischer-Tropsch technology, thecommercial SHELL® Middle Distillate Synthesis (SMDS) Process, or by thenon-commercial EXXON® Advanced Gas Conversion (AGC-21) process. Detailsof these processes and others are described in, for example, EP-A-776959, EP-A-668342; U.S. Pat. Nos. 4,943,672, 5,059,299, 5,733,839, andRE39073 ; and US Published Application No. 2005/0227866, WO-A-9934917,WO-A-9920720 and WO-A-05107935. The Fischer-Tropsch synthesis productusually comprises hydrocarbons having 1 to 100, or even more than 100carbon atoms, and typically includes paraffins, olefins and oxygenatedproducts. Fischer Tropsch is a viable process to generate cleanalternative hydrocarbon products.

There is still a need for engine oil compositions meeting ILSAC GF-4specifications, utilizing less common hydrocarbon products and withimproved fuel economy performance.

SUMMARY OF THE INVENTION

In one embodiment, there is provided an engine oil composition meetingat least one of ILSAC GF-4, API CI-4, API CJ4, ACEA A1, ACEA A5, ACEAB1, ACEA B5, ACEA C1, ACEA C2, ACEA C3, ACEA C4A, and JASO DL-1performance specifications, the composition comprising at least anisomerized base oil comprising a consecutive number of carbon atoms andhaving a CCS Viscosity at −35° C. of less than or equal to 7000 mPa, aT₉₅-T₅ boiling range distribution of less than or equal to 200° C., aratio of weight percent molecules with monocycloparaffinic functionalityto weight percent molecules with multicycloparaffinic functionality ofgreater than 15, and an Oxidator BN of greater than 30 hours; and 0.05to 40 wt %. of at least an additive selected from the group of metaldetergents, dispersants, wear inhibitors, anti-oxidants, frictionmodifiers, viscosity modifiers, corrosion inhibitors, seal swellingagents, metal deactivators, anti-foamants, and mixtures thereof. Theengine oil composition in one embodiment provides at least 1% fuelsavings over a composition of the prior art without the isomerized baseoil.

In another aspect, there is provided a method to improve fuel efficiencyin the operations of an automobile/vehicle, the method comprisesutilizing an engine oil composition at least an isomerized base oilcomprising a consecutive number of carbon atoms and having a CCSViscosity at −35° C. of less than or equal to 7000 mPa, a T₉₅-T₅ boilingrange distribution of less than or equal to 200° C., a ratio of weightpercent molecules with monocycloparaffinic functionality to weightpercent molecules with multicycloparaffinic functionality of greaterthan 15, and an Oxidator BN of greater than 30 hours; and 0.05 to 40 wt%. of at least an additive selected from the group of metal detergents,dispersants, wear inhibitors, anti-oxidants, friction modifiers,viscosity modifiers, corrosion inhibitors, seal swelling agents, metaldeactivators, anti-foamants, and mixtures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are graphs comparing the Traction Coefficient vs. DiskSpeed of embodiments of engine oil compositions comprising an isomerizedbase oil and embodiments of the engine oils of the prior art, containingGroup III base stock.

FIGS. 3 and 4 are graphs comparing the log₁₀ Traction Coefficient vs.Disk Speed at various slide to role ratio (SRR) values of embodiments ofengine oil compositions comprising an isomerized base oil andembodiments of the engine oils of the prior art, containing Group IIIbase stock.

DETAILED DESCRIPTION

The following terms will be used throughout the specification and willhave the following meanings unless otherwise indicated.

“Fischer-Tropsch derived” means that the product, fraction, or feedoriginates from or is produced at some stage by a Fischer-Tropschprocess. As used herein, “Fischer-Tropsch base oil” may be usedinterchangeably with “FT base oil,” “FTBO,” “GTL base oil” (GTL:gas-to-liquid), or “Fischer-Tropsch derived base oil.”

As used herein, “isomerized base oil” refers to a base oil made byisomerization of a waxy feed.

As used herein, a “waxy feed” comprises at least 40 wt % n-paraffins. Inone embodiment, the waxy feed comprises greater than 50 wt %n-paraffins. In another embodiment, greater than 75 wt % n-paraffins. Inone embodiment, the waxy feed also has very low levels of nitrogen andsulphur, e.g., less than 25 ppm total combined nitrogen and sulfur, orin other embodiments less than 20 ppm. Examples of waxy feeds includeslack waxes, deoiled slack waxes, refined foots oils, waxy lubricantraffinates, n-paraffin waxes, NAO waxes, waxes produced in chemicalplant processes, deoiled petroleum derived waxes, microcrystallinewaxes, Fischer-Tropsch waxes, and mixtures thereof In one embodiment,the waxy feeds have a pour point of greater than 50° C. In anotherembodiment, greater than 60° C.

“Kinematic viscosity” is a measurement in mm²/s of the resistance toflow of a fluid under gravity, determined by ASTM D445-06.

“Viscosity index” (VI) is an empirical, unit-less number indicating theeffect of temperature change on the kinematic viscosity of the oil. Thehigher the VI of an oil, the lower its tendency to change viscosity withtemperature. Viscosity index is measured according to ASTM D 2270-04.

Cold-cranking simulator apparent viscosity (CCS VIS) is a measurement inmillipascal seconds, mPa.s to measure the viscometric properties oflubricating base oils under low temperature and low shear. CCS VIS isdetermined by ASTM D 5293-04.

The boiling range distribution of base oil, by wt %, is determined bysimulated distillation (SIMDIS) according to ASTM D 6352-04, “BoilingRange Distribution of Petroleum Distillates in Boiling Range from 174 to700° C. by Gas Chromatography.”

“Noack volatility” is defined as the mass of oil, expressed in weight %,which is lost when the oil is heated at 250° C. with a constant flow ofair drawn through it for 60 min., measured according to ASTM D5800-05,Procedure B.

Brookfield viscosity is used to determine the internal fluid-friction ofa lubricant during cold temperature operation, which can be measured byASTM D 2983-04.

“Pour point” is a measurement of the temperature at which a sample ofbase oil will begin to flow under certain carefully controlledconditions, which can be determined as described in ASTM D 5950-02.

“Auto ignition temperature” is the temperature at which a fluid willignite spontaneously in contact with air, which can be determinedaccording to ASTM 659-78.

“Ln” refers to natural logarithm with base “e.”

“Traction coefficient” is an indicator of intrinsic lubricantproperties, expressed as the dimensionless ratio of the friction force Fand the normal force N, where friction is the mechanical force whichresists movement or hinders movement between sliding or rollingsurfaces. Traction coefficient can be measured with an MTM TractionMeasurement System from PCS Instruments, Ltd., configured with apolished 19 mm diameter ball (SAE AISI 52100 steel) angled at 220 to aflat 46 mm diameter polished disk (SAE AISI 52100 steel). The steel balland disk are independently measured at an average rolling speed of 3meters per second, a slide to roll ratio of 40 percent, and a load of 20Newtons. The roll ratio is defined as the difference in sliding speedbetween the ball and disk divided by the mean speed of the ball anddisk, i.e. roll ratio=(Speed1−Speed2)/((Speed1+Speed2)−/2).

As used herein, “consecutive numbers of carbon atoms” means that thebase oil has a distribution of hydrocarbon molecules over a range ofcarbon numbers, with every number of carbon numbers in-between. Forexample, the base oil may have hydrocarbon molecules ranging from C22 toC36 or from C30 to C60 with every carbon number in-between. Thehydrocarbon molecules of the base oil differ from each other byconsecutive numbers of carbon atoms, as a consequence of the waxy feedalso having consecutive numbers of carbon atoms. For example, in theFischer-Tropsch hydrocarbon synthesis reaction, the source of carbonatoms is CO and the hydrocarbon molecules are built up one carbon atomat a time. Petroleum-derived waxy feeds have consecutive numbers ofcarbon atoms. In contrast to an oil based on poly-alpha-olefin (“PAO”),the molecules of an isomerized base oil have a more linear structure,comprising a relatively long backbone with short branches. The classictextbook description of a PAO is a star-shaped molecule, and inparticular tridecane, which is illustrated as three decane moleculesattached at a central point. While a star-shaped molecule istheoretical, nevertheless PAO molecules have fewer and longer branchesthat the hydrocarbon molecules that make up the isomerized base oildisclosed herein.

“Molecules with cycloparaffinic functionality” mean any molecule thatis, or contains as one or more substituents, a monocyclic or a fusedmulticyclic saturated hydrocarbon group.

“Molecules with monocycloparaffinic functionality” mean any moleculethat is a monocyclic saturated hydrocarbon group of three to seven ringcarbons or any molecule that is substituted with a single monocyclicsaturated hydrocarbon group of three to seven ring carbons.

“Molecules with multicycloparaffinic functionality” mean any moleculethat is a fused multicyclic saturated hydrocarbon ring group of two ormore fused rings, any molecule that is substituted with one or morefused multicyclic saturated hydrocarbon ring groups of two or more fusedrings, or any molecule that is substituted with more than one monocyclicsaturated hydrocarbon group of three to seven ring carbons.

Molecules with cycloparaffinic functionality, molecules withmonocycloparaffinic functionality, and molecules withmulticycloparaffinic functionality are reported as weight percent andare determined by a combination of Field Ionization Mass Spectroscopy(FIMS), HPLC-UV for aromatics, and Proton NMR for olefins, further fullydescribed herein.

Oxidator BN measures the response of a lubricating oil in a simulatedapplication. High values, or long times to adsorb one liter of oxygen,indicate good stability. Oxidator BN can be measured via a Dornte-typeoxygen absorption apparatus (R. W. Dornte “Oxidation of White Oils,”Industrial and Engineering Chemistry, Vol. 28, page 26, 1936), under 1atmosphere of pure oxygen at 340° F., time to absorb 1000 ml of O₂ by100 g. of oil is reported. In the Oxidator BN test, 0.8 ml of catalystis used per 100 grams of oil. The catalyst is a mixture of solublemetal-naphthenates simulating the average metal analysis of usedcrankcase oil. The additive package is 80 millimoles of zincbispolypropylenephenyldithiophosphate per 100 grams of oil.

Molecular characterizations can be performed by methods known in theart, including Field Ionization Mass Spectroscopy (FIMS) and n-d-Manalysis (ASTM D 3238-95 (Re-approved 2005) with normalization). InFIMS, the base oil is characterized as alkanes and molecules withdifferent numbers of unsaturations. The molecules with different numbersof unsaturations may be comprised of cycloparaffins, olefins, andaromatics. If aromatics are present in significant amount, they would beidentified as 4-unsaturations. When olefins are present in significantamounts, they would be identified as 1-unsaturations. The total of the1-unsaturations, 2-unsaturations, 3-unsaturations, 4-unsaturations,5-unsaturations, and 6-unsaturations from the FIMS analysis, minus thewt % olefins by proton NMR, and minus the wt % aromatics by HPLC-UV isthe total weight percent of molecules with cycloparaffinicfunctionality. If the aromatics content was not measured, it was assumedto be less than 0.1 wt % and not included in the calculation for totalweight percent of molecules with cycloparaffinic functionality. Thetotal weight percent of molecules with cycloparaffinic functionality isthe sum of the weight percent of molecules with monocyclopraffinicfunctionality and the weight percent of molecules withmulticycloparaffinic functionality.

Molecular weights are determined by ASTM D2503-92(Reapproved 2002). Themethod uses thermoelectric measurement of vapour pressure (VPO). Incircumstances where there is insufficient sample volume, an alternativemethod of ASTM D2502-04 may be used; and where this has been used it isindicated.

Density is determined by ASTM D4052-96 (Reapproved 2002). The sample isintroduced into an oscillating sample tube and the change in oscillatingfrequency caused by the change in the mass of the tube is used inconjunction with calibration data to determine the density of thesample.

Weight percent olefins can be determined by proton-NMR according to thesteps specified herein. In most tests, the olefins are conventionalolefins, i.e. a distributed mixture of those olefin types havinghydrogens attached to the double bond carbons such as: alpha,vinylidene, cis, trans, and tri-substituted, with a detectable allylicto olefin integral ratio between 1 and 2.5. When this ratio exceeds 3,it indicates a higher percentage of tri or tetra substituted olefinsbeing present, thus other assumptions known in the analytical art can bemade to calculate the number of double bonds in the sample. A solutionof 5-10% of the sample in deuterochloroform can be prepared, giving anormal proton spectrum of at least 12 ppm spectral width.Tetramethylsilane (TMS) can be used as an internal reference standard.The instrument used to acquire the spectrum and reference the chemicalshift has sufficient gain range to acquire a signal without overloadingthe receiver/ADC, with a minimum signal digitization dynamic range of atleast 65,000 when a 30 degree pulse is applied. The intensities of theproton signals in the region of 0.5-1.9 ppm (methyl, methylene andmethine groups), 1.9-2.2 ppm (allylic) and between 6.0-4.5 ppm (olefin)are measured. Using the average molecular weight (estimated by vaporpressure osmometry by ASTM D 2503-92[re-approved 2002]) of eachdistillate range paraffin feed, the following can be calculated: (1) theaverage molecular formula of the saturated hydrocarbons; (2) the averagemolecular formula of the olefins; (3) the total integral intensity (i.e.the sum of all the integral intensities); (4) the integral intensity persample hydrogen (i.e. the total integral intensity divided by the numberof hydrogens in the formula; (5) the number of olefin hydrogens (i.e.the olefin integral divided by the integral per hydrogen); (6) thenumber of double bonds (i.e. the olefin hydrogen multiplied by thehydrogens in the olefin formula divided by 2); and (7) the weightpercent olefins (i.e. 100 multiplied by the number of double bondsmultiplied by the number of hydrogens in a typical olefin moleculedivided by the number of hydrogens in a typical distillate rangeparaffin feed molecule). This Proton NMR procedure to calculate theolefin content of the sample works best when the olefin content is low,e.g., less than about 15 weight percent.

Weight percent aromatics in one embodiment can be measured by HPLC-UV.In one embodiment, the test is conducted using a Hewlett Packard 1050Series Quaternary Gradient High Performance Liquid Chromatography (HPLC)system, coupled with a HP 1050 Diode-Array UV-Vis detector interfaced toan HP Chem-station. Identification of the individual aromatic classes inthe highly saturated base oil can be made on the basis of the UVspectral pattern and the elution time. The amino column used for thisanalysis differentiates aromatic molecules largely on the basis of theirring- number (or double-bond number). Thus, the single ring aromaticcontaining molecules elute first, followed by the polycyclic aromaticsin order of increasing double bond number per molecule. For aromaticswith similar double bond character, those with only alkyl substitutionon the ring elute sooner than those with naphthenic substitution.Unequivocal identification of the various base oil aromatic hydrocarbonsfrom their UV absorbance spectra can be accomplished recognizing thattheir peak electronic transitions are all red-shifted relative to thepure model compound analogs to a degree dependent on the amount of alkyland naphthenic substitution on the ring system. Quantification of theeluting aromatic compounds can be made by integrating chromatograms madefrom wavelengths optimized for each general class of compounds over theappropriate retention time window for that aromatic. Retention timewindow limits for each aromatic class can be determined by manuallyevaluating the individual absorbance spectra of eluting compounds atdifferent times and assigning them to the appropriate aromatic classbased on their qualitative similarity to model compound absorptionspectra.

Weight percent aromatic carbon (“Ca”), weight percent naphthenic carbon(“Cn”) and weight percent paraffinic carbon (“Cp”) in one embodiment canbe measured by ASTM D3238-95 (Reapproved 2005) with normalization. ASTMD3238-95 (Reapproved 2005) is the Standard Test Method for Calculationof Carbon Distribution and Structural Group Analysis of Petroleum Oilsby the n-d-M Method. This method is for “olefin free” feedstocks, i.e.,having an olefin content of 2 wt % or less. The normalization processconsists of the following: A) If the Ca value is less than zero, Ca isset to zero, and Cn and Cp are increased proportionally so that the sumis 100%. B) If the Cn value is less than zero, Cn is set to zero, and Caand Cp are increased proportionally so that the sum is 100%; and C) Ifboth Cn and Ca are less than zero, Cn and Ca are set to zero, and Cp isset to 100%.

HPLC-UV Calibration. In one embodiment, HPLC-UV can be used foridentifying classes of aromatic compounds even at very low levels, e.g.,multi-ring aromatics typically absorb 10 to 200 times more strongly thansingle-ring aromatics. Alkyl-substitution affects absorption by 20%.Integration limits for the co-eluting 1-ring and 2-ring aromatics at 272nm can be made by the perpendicular drop method. Wavelength dependentresponse factors for each general aromatic class can be first determinedby constructing Beer's Law plots from pure model compound mixtures basedon the nearest spectral peak absorbances to the substituted aromaticanalogs. Weight percent concentrations of aromatics can be calculated byassuming that the average molecular weight for each aromatic class wasapproximately equal to the average molecular weight for the whole baseoil sample.

NMR analysis. In one embodiment, the weight percent of all moleculeswith at least one aromatic function in the purified mono-aromaticstandard can be confirmed via long-duration carbon 13 NMR analysis. TheNMR results can be translated from % aromatic carbon to % aromaticmolecules (to be consistent with HPLC-UV and D 2007) knowing that 95-99%of the aromatics in highly saturated base oils are single-ringaromatics. In another test to accurately measure low levels of allmolecules with at least one aromatic function by NMR, the standard D5292-99 (Reapproved 2004) method can be modified to give a minimumcarbon sensitivity of 500:1 (by ASTM standard practice E 386) with a15-hour duration run on a 400-500 MHz NMR with a 10-12 mm Nalorac probe.Acorn PC integration software can be used to define the shape of thebaseline and consistently integrate.

Extent of branching refers to the number of alkyl branches inhydrocarbons. Branching and branching position can be determined usingcarbon-13 (¹³C) NMR according to the following nine-step process: 1)Identify the CH branch centers and the CH₃ branch termination pointsusing the DEPT Pulse sequence (Doddrell, D. T.; D. T. Pegg; M. R.Bendall, Journal of Magnetic Resonance 1982, 48, 323ff.). 2) Verify theabsence of carbons initiating multiple branches (quaternary carbons)using the APT pulse sequence (Patt, S. L.; J. N. Shoolery, Journal ofMagnetic Resonance 1982, 46, 535ff.). 3) Assign the various branchcarbon resonances to specific branch positions and lengths usingtabulated and calculated values known in the art (Lindeman, L. P.,Journal of Qualitative Analytical Chemistry 43, 1971 1245ff; Netzel, D.A., et. al., Fuel, 60, 1981, 307ff). 4) Estimate relative branchingdensity at different carbon positions by comparing the integratedintensity of the specific carbon of the methyl/alkyl group to theintensity of a single carbon (which is equal to total integral/number ofcarbons per molecule in the mixture). For the 2-methyl branch, whereboth the terminal and the branch methyl occur at the same resonanceposition, the intensity is divided by two before estimating thebranching density. If the 4-methyl branch fraction is calculated andtabulated, its contribution to the 4+methyls is subtracted to avoiddouble counting. 5) Calculate the average carbon number. The averagecarbon number is determined by dividing the molecular weight of thesample by 14 (the formula weight of CH₂). 6) The number of branches permolecule is the sum of the branches found in step 4. 7) The number ofalkyl branches per 100 carbon atoms is calculated from the number ofbranches per molecule (step 6) times 100/average carbon number. 8)Estimate Branching Index (BI) by ¹H NMR Analysis, which is presented aspercentage of methyl hydrogen (chemical shift range 0.6-1.05 ppm) amongtotal hydrogen as estimated by NMR in the liquid hydrocarboncomposition. 9) Estimate Branching proximity (BP) by ¹³C NMR, which ispresented as percentage of recurring methylene carbons—which are four ormore carbons away from the end group or a branch (represented by a NMRsignal at 29.9 ppm) among total carbons as estimated by NMR in theliquid hydrocarbon composition. The measurements can be performed usingany Fourier Transform NMR spectrometer, e.g., one having a magnet of 7.0T or greater. After verification by Mass Spectrometry, UV or an NMRsurvey that aromatic carbons are absent, the spectral width for the ¹³CNMR studies can be limited to the saturated carbon region, 0-80 ppm vs.TMS (tetramethylsilane). Solutions of 25-50 wt. % in chloroform-d1 areexcited by 30 degrees pulses followed by a 1.3 seconds (sec.)acquisition time. In order to minimize non-uniform intensity data, thebroadband proton inverse-gated decoupling is used during a 6 sec. delayprior to the excitation pulse and on during acquisition. Samples aredoped with 0.03 to 0.05 M Cr (acac)₃ (tris(acetylacetonato)-chromium(III)) as a relaxation agent to ensure full intensities are observed.The DEPT and APT sequences can be carried out according to literaturedescriptions with minor deviations described in the Varian or Brukeroperating manuals. DEPT is Distortionless Enhancement by PolarizationTransfer. The DEPT 45 sequence gives a signal all carbons bonded toprotons. DEPT 90 shows CH carbons only. DEPT 135 shows CH and CH₃ up andCH₂ 180 degrees out of phase (down). APT is attached proton test, knownin the art. It allows all carbons to be seen, but if CH and CH₃ are up,then quaternaries and CH₂ are down. The branching properties of thesample can be determined by ¹³C NMR using the assumption in thecalculations that the entire sample was iso-paraffinic. The unsaturatescontent may be measured using Field Ionization Mass Spectroscopy (FIMS).

In one embodiment, the engine oil composition comprises optionaladditives in a matrix of base oil or base oil blends comprising xxxxxx.

Base Oil Component: In one embodiment, the base oil or blend thereofcomprises at least an isomerized base oil which the product itself, itsfraction, or feed originates from or is produced at some stage byisomerization of a waxy feed from a Fischer-Tropsch process(“Fischer-Tropsch derived base oils”). In another embodiment, the baseoil comprises at least an isomerized base oil made from a substantiallyparaffinic wax feed (“waxy feed”). In a third embodiment, the isomerizedbase oil comprises mixtures of products made from a substantiallyparaffinic wax feed as well as products made from a waxy feed from aFischer-Tropsch process.

Fischer-Tropsch derived base oils are disclosed in a number of patentpublications, including for example U.S. Pat. Nos. 6,080,301, 6,090,989,and 6,165,949, and US Patent Publication No. US2004/0079678A1,US20050133409, US20060289337. The Fischer-Tropsch process is a catalyzedchemical reaction in which carbon monoxide and hydrogen are convertedinto liquid hydrocarbons of various forms including a light reactionproduct and a waxy reaction product, with both being substantiallyparaffinic.

In one embodiment the isomerized base oil has consecutive numbers ofcarbon atoms and has less than 25 wt % naphthenic carbon by n-d-M withnormalization. In another embodiment, the amount of naphthenic carbon isless than 10 wt. %. In yet another embodiment the isomerized base oilmade from a waxy feed has a kinematic viscosity at 100° C. between 1.5and 3.5 mm²/s.

In one embodiment, the isomerized base oil is made by a process in whichthe hydroisomerization dewaxing is performed at conditions sufficientfor the base oil to have: a) a weight percent of all molecules with atleast one aromatic functionality less than 0.30; b) a weight percent ofall molecules with at least one cycloparaffinic functionality greaterthan 10; c) a ratio of weight percent molecules with monocycloparaffinicfunctionality to weight percent molecules with multicycloparaffinicfunctionality greater than 20 and d) a viscosity index greater than28×Ln (Kinematic viscosity at 100° C.)+80.

In another embodiment, the isomerized base oil is made from a process inwhich the highly paraffinic wax is hydroisomerized using a shapeselective intermediate pore size molecular sieve comprising a noblemetal hydrogenation component, and under conditions of 600-750° F.(315-399° C.) In the process, the conditions for hydroisomerization arecontrolled such that the conversion of the compounds boiling above 700°F. (371° C.) in the wax feed to compounds boiling below 700° F. (371°C.) is maintained between 10 wt % and 50 wt %. A resulting isomerizedbase oil has a kinematic viscosity of between 1.0 and 3.5 mm²/s at 100°C. and a Noack volatility of less than 50 weight %. The base oilcomprises greater than 3 weight % molecules with cycloparaffinicfunctionality and less than 0.30 weight percent aromatics.

In one embodiment the isomerized base oil has a Noack volatility lessthan an amount calculated by the following equation: 1000×(KinematicViscosity at 100° C.)^(−2.7). In another embodiment, the isomerized baseoil has a Noack volatility less than an amount calculated by thefollowing equation: 900×(Kinematic Vicosity at 100° C.)^(−2.8). In athird embodiment, the isomerized base oil has a Kinematic Viscosity at100° C. of >1.808 mm²/s and a Noack volatility less than an amountcalculated by the following equation: 1.286+20 (kV100)^(−1.5)+551.8e^(−kv100), where kv100 is the kinematic viscosity at 100° C. In afourth embodiment, the isomerized base oil has a kinematic viscosity at100° C. of less than 4.0 mm²/s, and a wt % Noack volatility between 0and 100. In a fifth embodiment, the isomerized base oil has a kinematicviscosity between 1.5 and 4.0 mm²/s and a Noack volatility less than theNoack volatility calculated by the following equation: 160−40 (KinematicViscosity at 100° C.).

In one embodiment, the isomerized base oil has a kinematic viscosity at100° C. in the range of 2.4 and 3.8 mm²/s and a Noack volatility lessthan an amount defined by the equation: 900×(Kinematic Viscosity at 100°C.)^(−2.8)−15). For kinematic viscosities in the range of 2.4 and 3.8mm²/s, the equation: 900×(Kinematic Viscosity at 100° C.)^(−2.8)−15)provides a lower Noack volatility than the equation: 160−40 (KinematicViscosity at 100° C.)

In one embodiment, the isomerized base oil is made from a process inwhich the highly paraffinic wax is hydroisomerized under conditions forthe base oil to have a kinematic viscosity at 100° C. of 3.6 to 4.2mm²/s, a viscosity index of greater than 130, a wt % Noack volatilityless than 12, a pour point of less than −9° C.

In one embodiment, the isomerized base oil has an aniline point, indegrees F, greater than 200 and less than or equal to an amount definedby the equation: 36×Ln(Kinematic Viscosity at 100° C., in mm²/s)+200.

In one embodiment, the isomerized base oil has an auto-ignitiontemperature (AIT) greater than the AIT defined by the equation: AIT in °C.=1.6×(Kinematic Viscosity at 40° C., in mm2/s)+300. In a secondembodiment, the base oil as an AIT of greater than 329° C. and aviscosity index greater than 28×Ln (Kinematic Viscosity at 100° C., inmm²/s)+100.

In one embodiment, the isomerized base oil has a relatively low tractioncoefficient, specifically, its traction coefficient is less than anamount calculated by the equation: traction coefficient=0.009×Ln(kinematic viscosity in mm²/s)−0.001, wherein the kinematic viscosity inthe equation is the kinematic viscosity during the traction coefficientmeasurement and is between 2 and 50 mm²/s. In one embodiment, theisomerized base oil has a traction coefficient of less than 0.023 (orless than 0.021) when measured at a kinematic viscosity of 15 mm²/s andat a slide to roll ratio of 40%. In another embodiment the isomerizedbase oil has a traction coefficient of less than 0.017 when measured ata kinematic viscosity of 15 mm²/s and at a slide to roll ratio of 40%.In another embodiment the isomerized base oil has a viscosity indexgreater than 150 and a traction coefficient less than 0.015 whenmeasured at a kinematic viscosity of 15 mm²/s and at a slide to rollratio of 40 percent.

In some embodiments, the isomerized base oil having low tractioncoefficients also displays a higher kinematic viscosity and higherboiling points. In one embodiment, the base oil has a tractioncoefficient less than 0.015, and a 50 wt % boiling point greater than565° C. (1050° F.). In another embodiment, the base oil has a tractioncoefficient less than 0.011 and a 50 wt % boiling point by ASTM D6352-04 greater than 582° C. (1080° F.).

In some embodiments, the isomerized base oil having low tractioncoefficients also displays unique branching properties by NMR, includinga branching index less than or equal to 23.4, a branching proximitygreater than or equal to 22.0, and a Free Carbon Index between 9 and 30.In one embodiment, the base oil has at least 4 wt % naphthenic carbon,in another embodiment, at least 5 wt % naphthenic carbon by n-d-Manalysis by ASTM D 3238-95 (Reapproved 2005) with normalization.

In one embodiment, the isomerized base oil is produced in a processwherein the intermediate oil isomerate comprises paraffinic hydrocarboncomponents, and in which the extent of branching is less than 7 alkylbranches per 100 carbons, and wherein the base oil comprises paraffinichydrocarbon components in which the extent of branching is less than 8alkyl branches per 100 carbons and less than 20 wt % of the alkylbranches are at the 2 position. In one embodiment, the FT base oil has apour point of less than −8° C.; a kinematic viscosity at 100° C. of atleast 3.2 mm²/s; and a viscosity index greater than a viscosity indexcalculated by the equation of=22×Ln (kinematic viscosity at 100°C.)+132.

In one embodiment, the base oil comprises greater than 10 wt. % and lessthan 70 wt. % total molecules with cycloparaffinic functionality, and aratio of weight percent molecules with monocycloparaffinic functionalityto weight percent molecules with multicycloparaffinic functionalitygreater than 15.

In one embodiment, the isomerized base oil has an average molecularweight between 600 and 1100, and an average degree of branching in themolecules between 6.5 and 10 alkyl branches per 100 carbon atoms. Inanother embodiment, the isomerized base oil has a kinematic viscositybetween about 8 and about 25 mm²/s and an average degree of branching inthe molecules between 6.5 and 10 alkyl branches per 100 carbon atoms.

In one embodiment, the isomerized base oil is obtained from a process inwhich the highly paraffinic wax is hydroisomerized at a hydrogen to feedratio from 712.4 to 3562 liter H₂/liter oil, for the base oil to have atotal weight percent of molecules with cycloparaffinic functionality ofgreater than 10, and a ratio of weight percent molecules withmonocycloparaffinic functionality to weight percent molecules withmulticycloparaffinic functionality of greater than 15. In anotherembodiment, the base oil has a viscosity index greater than an amountdefined by the equation: 28×Ln (Kinematic viscosity at 100° C.)+95. In athird embodiment, the base oil comprises a weight percent aromatics lessthan 0.30; a weight percent of molecules with cycloparaffinicfunctionality greater than 10; a ratio of weight percent of moleculeswith monocycloparaffinic functionality to weight percent of moleculeswith multicycloparaffinic functionality greater than 20; and a viscosityindex greater than 28×Ln (Kinematic Viscosity at 100° C.)+110. In afourth embodiment, the base oil further has a kinematic viscosity at100° C. greater than 6 mm²/s. In a fifth embodiment, the base oil has aweight percent aromatics less than 0.05 and a viscosity index greaterthan 28×Ln (Kinematic Viscosity at 100° C.)+95. In a sixth embodiment,the base oil has a weight percent aromatics less than 0.30, a weightpercent molecules with cycloparaffinic functionality greater than thekinematic viscosity at 100° C., in mm²/s, multiplied by three, and aratio of molecules with monocycloparaffinic functionality to moleculeswith multicycloparaffinic functionality greater than 15.

In one embodiment, the isomerized base oil contains between 2 and 10 wt% naphthenic carbon as measured by n-d-M. In one embodiment, the baseoil has a kinematic viscosity of 1.5-3.0 mm²/s at 100° C. and 2-3 wt %naphthenic carbon. In another embodiment, a kinematic viscosity of1.8-3.5 mm²/s at 100° C. and 2.5-4 wt % naphthenic carbon. In a thirdembodiment, a kinematic viscosity of 3-6 mm²/s at 100° C. and 2.7-5 wt %naphthenic carbon. In a fourth embodiment, a kinematic viscosity of10-30 mm²/s at 100° C. and between greater than 5.2 % and less than 25wt % naphthenic carbon.

In one embodiment, the isomerized base oil has an average molecularweight greater than 475; a viscosity index greater than 140, and aweight percent olefins less than 10. The base oil improves the airrelease and low foaming characteristics of the mixture when incorporatedinto the engine oil composition.

In one embodiment, the isomerized base oil is a FT base oil having akinematic viscosity at 100° C. between 3 mm²/s and 10 mm²/s; a viscosityindex between 135 and 160; CCS VIS in the range of 1,000-7,500 mPa.s at−35° C.; pour point in the range of −20 and −30° C.; Oxidator BN of 35to 50 hours; and Noack volatility in wt. % of 2 to 20 as measured byASTM D5800-05 Procedure B.

In one embodiment, the engine oil composition employs a base oil thatconsists of at least one of the isomerized base oils described above. Inanother embodiment, the composition consists essentially of at least aFischer-Tropsch base oil. In yet another embodiment, the compositionemploys at least a Fischer-Tropsch base oil and optionally 5 to 30 wt. %of at least another type of oil, e.g., lubricant base oils selected fromGroup I, II, III, IV, and V lubricant base oils as defined in the APIInterchange Guidelines, and mixtures thereof Examples includeconventionally used mineral oils, synthetic hydrocarbon oils orsynthetic ester oils, or mixtures thereof depending on the application.Mineral lubricating oil base stocks can be any conventionally refinedbase stocks derived from paraffinic, naphthenic and mixed base crudes.Synthetic lubricating oils that can be used include esters of glycolsand complex esters. Other synthetic oils that can be used includesynthetic hydrocarbons such as polyalphaolefins; alkyl benzenes, e.g.,alkylate bottoms from the alkylation of benzene with tetrapropylene, orthe copolymers of ethylene and propylene; silicone oils, e.g., ethylphenyl polysiloxanes, methyl polysiloxanes, etc., polyglycol oils, e.g.,those obtained by condensing butyl alcohol with propylene oxide; etc.Other suitable synthetic oils include the polyphenyl ethers, e.g., thosehaving from 3 to 7 ether linkages and 4 to 8 phenyl groups. Othersuitable synthetic oils include polyisobutenes, and alkylated aromaticssuch as alkylated naphthalenes.

Additional Components: In one embodiment, the engine oil furthercomprises at least an additive selected from the group of metaldetergents, dispersants, wear inhibitors, oxidation inhibitors, frictionmodifiers, viscosity modifiers, corrosion inhibitors, seal swellingagents, metal deactivators, antifoamers, and mixtures thereof, in asufficient amount to provide the desired effects. In one embodiment,this sufficient amount is 0.05 to 40 wt. %. In another embodiment, it isbetween 1 to 35 wt. %. In a third embodiment, from 5 to 25 wt. %.

In one embodiment, the additives are incorporated as an “additivepackage.” As used herein, the term “additive package” means anycombination of additives listed above for engine oil compositions. Inone embodiment, the additive package is a commercially availablepackage, added in an amount from about 1.5% to about 30% by weight ofthe finished composition. In one embodiment, the additive package is acommercially available package from the Lubrizol Corporation or fromChevron Oronite Company LLC.

Dispersants: Dispersants are generally used to maintain in suspensioninsoluble materials resulting from oxidation during use, thus preventingsludge flocculation and precipitation or deposition on engine parts. Inone embodiment, the composition comprises 0.3 to about 15.0 wt. % of atleast a dispersant. In a second embodiment, from 3.0 to about 7.0 wt. %of at least a dispersant. Examples of dispersants includenitrogen-containing ashless (metal-free) dispersants. An ashlessdispersant generally comprises an oil soluble polymeric hydrocarbonbackbone having functional groups that are capable of associating withparticles to be dispersed. Other examples of dispersants include, butare not limited to, amines, alcohols, amides, or ester polar moietiesattached to the polymer backbones via bridging groups.

In one embodiment, the engine oil composition comprises an ashlessdispersant selected from oil soluble salts, esters, amino-esters,amides, imides, and oxazolines of long chain hydrocarbon substitutedmono and dicarboxylic acids or their anhydrides; thiocarboxylatederivatives of long chain hydrocarbons, long chain aliphatichydrocarbons having a polyamine attached directly thereto; and Mannichcondensation products formed by condensing a long chain substitutedphenol with formaldehyde and polyalkylene polyamine. In anotherembodiment, the composition comprises at least a carboxylic dispersant.Carboxylic dispersants are reaction products of carboxylic acylatingagents (acids, anhydrides, esters, etc.) comprising at least 34 andpreferably at least 54 carbon atoms with nitrogen containing compounds(such as amines), organic hydroxy compounds (such as aliphatic compoundsincluding monohydric and polyhydric alcohols, or aromatic compoundsincluding phenols and naphthols), and/or basic inorganic materials.These reaction products include imides, amides, and esters, e.g.,succinimide dispersants.

Other suitable ashless dispersants may also include amine dispersants,which are reaction products of relatively high molecular weightaliphatic halides and amines, preferably polyalkylene polyamines. Otherexamples may further include “Mannich dispersants,” which are reactionproducts of alkyl phenols in which the alkyl group contains at least 30carbon atoms with aldehydes (especially formaldehyde) and amines(especially polyalkylene polyamines). In other embodiments, suitableashless dispersants may even include post-treated dispersants, which areobtained by reacting carboxylic, amine or Mannich dispersants withreagents such as dimercaptothiazoles, urea, thiourea, carbon disulfide,aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinicanhydrides, nitrile epoxides, boron compounds and the like. Suitableashless dispersants may be polymeric, which are interpolymers ofoil-solubilizing monomers such as decyl methacrylate, vinyl decyl etherand high molecular weight olefins with monomers containing polarsubstitutes.

In one embodiment, an ethylene carbonate-treated bissuccinimide derivedfrom a polyisobutylene having a number average molecular weight of about2300 Daltons is used as the ashless dispersant. In yet anotherembodiment, the engine oil composition comprises an ethylene-carbonatetreated bissuccinimide dispersant derived from a polyisobutylenesuccinic anhydride, wherein the polyisobutylene chain has a numberaverage molecular weight of about 2300 Daltons (“PIBSA 2300”) in anamount of about 6.5 wt. %.

Viscosity Index Improvers (Modifiers): The viscosity index of an engineoil base stock can be increased, or improved, by incorporating thereincertain polymeric materials that function as viscosity modifiers (VM) orviscosity index improvers (VII) in an amount of 0.3 to 25 wt. %. of thefinal weight of the engine oil. Examples include but are not limited toolefin copolymers, such as ethylene-propylene copolymers,styrene-isoprene copolymers, hydrated styrene-isoprene copolymers,polybutene, polyisobutylene, polymethacrylates, vinylpyrrolidone andmethacrylate copolymers and dispersant type viscosity index improvers.These viscosity modifiers can optionally be grafted with graftingmaterials such as, for example, maleic anhydride, and the graftedmaterial can be reacted with, for example, amines, amides,nitrogen-containing heterocyclic compounds or alcohol, to formmultifunctional viscosity modifiers (dispersant-viscosity modifiers).

In one embodiment, the engine oil composition comprises about 0.3 to 15wt. % of an ethylene propylene copolymer viscosity index modifier. Otherexamples of viscosity modifiers include star polymers, e.g., a starpolymer comprising isoprene/styrene/isoprene triblock. Yet otherexamples of viscosity modifiers include poly alkyl(meth)acrylates of lowBrookfield viscosity and high shear stability, functionalized polyalkyl(meth)acrylates with dispersant properties of high Brookfieldviscosity and high shear stability, polyisobutylene having a weightaverage molecular weight ranging from 700 to 2,500 Daltons and mixturesthereof.

Friction Modifiers: In one embodiment, the lubricating oil compositionfurther comprises at least a friction modifier, e.g., asulfur-containing molybdenum compound. In some embodiments, thecomposition does not contain any friction modifier at all (or just aminimal amount, e.g., less than 0.1 wt. %) while still providingexcellent fuel economy performance. Certain sulfur-containingorgano-molybdenum compounds are known to modify friction in lubricatingoil compositions, while also offering antioxidant and antiwear credits.Examples of oil soluble organo-molybdenum compounds includedithiocarbamates, dithiophosphates, dithiophosphinates, xanthates,thioxanthates, sulfides, and the like, and mixtures thereof. In anotherembodiment, the composition employs a molybdenum succinimide complex asfriction modifier in an amount of 0.15 to about 1.5 wt. %. In a thirdembodiment, the engine oil composition comprises at least a mono-, di-or triester of a tertiary hydroxyl amine and a fatty acid as a frictionmodifying fuel economy additive. In another embodiment, the frictionmodifier is selected from the group of succinamic acid, succinimide, andmixtures thereof. In yet another embodiment, the friction modifier isselected from an aliphatic fatty amine, an ether amine, an alkoxylatedaliphatic fatty amine, an alkoxylated ether amine, an oil-solublealiphatic carboxylic acid, a polyol ester, a fatty acid amide, animidazoline, a tertiary amine, a hydrocarbyl succinic anhydride or acidreacted with an ammonia or a primary amine, and mixtures thereof.

Seal swelling agents: Seal fixes are also termed seal swelling agents orseal pacifiers. They are often employed in lubricant or additivecompositions to insure proper elastomer sealing, and prevent prematureseal failures and leakages. In one embodiment, the composition furtherincludes at least a seal swell agent selected from oil-soluble,saturated, aliphatic, or aromatic hydrocarbon esters such asdi-2-ethylhexylphthalate, mineral oils with aliphatic alcohols such astridecyl alcohol, triphosphite ester in combination with ahydrocarbonyl-substituted phenol, and di-2-ethylhexylsebacate.

Corrosion inhibitors (Anti-corrosive agents): These additives aretypically added to reduce the degradation of the metallic partscontained in the engine oil in amounts from about 0.02 to 1 wt. %.Examples include zinc dialkyldithiophosphate, phosphosulfurizedhydrocarbons and the products obtained by reaction of aphosphosulfurized hydrocarbon with an alkaline earth metal oxide orhydroxide, preferably in the presence of an alkylated phenol or of analkylphenol thioester. In one embodiment, the rust inhibitor oranticorrosion agents may be a nonionic polyoxyethylene surface activeagent. Nonionic polyoxyethylene surface active agents include, but arenot limited to, polyoxyethylene lauryl ether, polyoxyethylene higheralcohol ether, polyoxyethylene nonylphenyl ether, polyoxyethyleneoctylphenyl ether, polyoxyethylene octyl stearyl ether, polyoxyethyleneoleyl ether, polyoxyethylene sorbitol monostearate, polyoxyethylenesorbitol mono-oleate, and polyethylene glycol monooleate. Rustinhibitors or anticorrosion agents may also be other compounds, whichinclude, for example, stearic acid and other fatty acids, dicarboxylicacids, metal soaps, fatty acid amine salts, metal salts of heavysulfonic acid, partial carboxylic acid ester of polyhydric alcohols, andphosphoric esters. In another embodiment, the rust inhibitor is acalcium stearate salt.

Detergents: In engine oil compositions, metal-containing or ash-formingdetergents function both as detergents to reduce or remove deposits andas acid neutralizers or rust inhibitors, thereby reducing wear andcorrosion and extending engine life. Detergents generally comprise apolar head with long hydrophobic tail, with the polar head comprising ametal salt of an acid organic compound.

In one embodiment, the engine oil composition contains one or moredetergents, which are normally salts, e.g., overbased salts. Overbasedsalts, or overbased materials, are single phase, homogeneous Newtoniansystems characterized by a metal content in excess of that which wouldbe present according to the stoichiometry of the metal and theparticular acidic organic compound reacted with the metal. In anotherembodiment, the engine oil composition comprises at least a carboxylatedetergent. Carboxylate detergents, e.g., salicylates, can be prepared byreacting an aromatic carboxylic acid with an appropriate metal compoundsuch as an oxide or hydroxide. In yet another embodiment, the engine oilcomposition comprises at least an overbased detergent. Examples of theoverbased detergents include, but are not limited to calcium sulfonates,calcium phenates, calcium salicylates, calcium stearates and mixturesthereof. Overbased detergents may be low overbased (e.g., Total BaseNumber (TBN) below about 50). Suitable overbased detergents mayalternatively be high overbased (e.g., TBN above about 150) or mediumoverbased (e.g., TBN between 50 and 150). The lubricating oilcompositions may comprise more than one overbased detergents, which maybe all low-TBN detergents, all high-TBN detergents, or a mix of thosetwo types. Other suitable detergents for the lubricating oilcompositions include “hybrid” detergents such as, for example,phenate/salicylates, sulfonate/phenates, sulfonate/salicylates,sulfonates/phenates/salicylates, and the like. In other embodiments, thecomposition comprises detergents made from alkyl benzene and fumingsulfonic acid, phenates (high overbased, medium overbased, or lowoverbased), high overbased phenate stearates, phenolates, salicylates,phosphonates, thiophosphonates, sulfonates, carboxylates, ionicsurfactants and sulfonates and the like.

Oxidation Inhibitors/Antioxidants: Oxidation inhibitors or antioxidantsreduce the tendency of mineral oils to deteriorate in service, whichdeterioration is evidenced by the products of oxidation such as sludge,lacquer, and varnish-like deposits on metal surfaces. In one embodiment,the engine oil composition contains from about 50 ppm to about 5.00 wt.% of at least an antioxidant selected from the group of phenolicantioxidants, aminic antioxidants, or a combination thereof. In otherembodiments, the amount of antioxidants is between 0.10 to 3.00 wt. %.In yet other embodiments, ranging from about 0.20 to 0.80 wt. %. Anexample of an antioxidant used is di-C₈-diphenylamine, in an amount ofabout 0.05 to 2.00 wt. % of the total weight of the oil composition.Other examples of antioxidants include MoS and Mo oxide compounds.

Other examples of antioxidants include hindered phenols; alkaline earthmetal salts of alkylphenolthioesters having C₅ to C₁₂ alkyl side chains;calcium nonylphenol sulphide; oil soluble phenates and sulfurizedphenates; phosphosulfurized or sulfurized hydrocarbons or esters;phosphorous esters; metal thiocarbamates; oil soluble copper compoundsknown in the art; phenyl naphthyl amines such as phenylene diamine,phenothiazine, diphenyl amine, diarylamine; phenyl-alphanaphthylamine,2,2′-diethyl-4,4′-dioctyl diphenylamine,2,2′diethyl-4-t-octyldiphenylamine; alkaline earth metal salts ofalkylphenol thioesters, having C₅ to C₁₂ alkyl side chains, e.g.,calcium nonylphenol sulfide, barium t-octylphenol sulfide, zincdialkylditbiophosphates, dioctylphenylamine, phenylalphanaphthylamineand mixtures thereof. Some of these antioxidants further function ascorrosion inhibitors. Other suitable antioxidants which also function asantiwear agents include bis alkyl dithiothiadiazoles such as2,5-bis-octyl dithiothiadiazole.

Anti-foamants: In one embodiment, the engine oil further comprises ananti-foamant (foam inhibitor) in amounts ranging from about 5 to about50 ppm. Examples include alkyl methacrylate polymers, dimethyl siliconepolymers, and foam inhibitors of the polysiloxane type, e.g., siliconeoil and polydimethyl siloxane, for foam control. In another embodiment,the anti-foamant is a mixture of polydimethyl siloxane andfluorosilicone. In yet another embodiment, the engine oil furthercomprises an acrylate polymer anti-foamant, with a weight ratio of thefluorosilicone antifoamant to the acrylate anti-foamant ranging fromabout 3:1 to about 1:4. In a fourth embodiment, the engine oil comprisesan anti-foam-effective amount of a silicon-containing anti-foamant suchthat the total amount of silicon in the engine oil is at least 30 ppm.In yet another embodiment, the silicon-containing antifoam agent isselected from the group consisting of fluorosilicones,polydimethylsiloxane, phenyl-methyl polysiloxane, linear siloxanes,cyclic siloxanes, branched siloxanes, silicone polymers and copolymers,organo-silicone copolymers, and mixtures thereof.

Seal swelling agents: Seal fixes are also termed seal swelling agents orseal pacifiers. They are often employed in lubricant or additivecompositions to insure proper elastomer sealing, and prevent prematureseal failures and leakages. In one embodiment, the composition furtherincludes at least a seal swell agent selected from oil-soluble,saturated, aliphatic, or aromatic hydrocarbon esters such asdi-2-ethylhexylphthalate, mineral oils with aliphatic alcohols such astridecyl alcohol, triphosphite ester in combination with ahydrocarbonyl-substituted phenol, and di-2-ethylhexylsebacate.

Corrosion inhibitors (Anti-corrosive agents): These additives aretypically added to reduce the degradation of the metallic partscontained in the engine oil. Examples include zincdialkyldithiophosphate, phosphosulfurized hydrocarbons and the productsobtained by reaction of a phosphosulfurized hydrocarbon with an alkalineearth metal oxide or hydroxide, preferably in the presence of analkylated phenol or of an alkylphenol thioester. In one embodiment, therust inhibitor or anticorrosion agents may be a nonionic polyoxyethylenesurface active agent. Nonionic polyoxyethylene surface active agentsinclude, but are not limited to, polyoxyethylene lauryl ether,polyoxyethylene higher alcohol ether, polyoxyethylene nonylphenyl ether,polyoxyethylene octylphenyl ether, polyoxyethylene octyl stearyl ether,polyoxyethylene oleyl ether, polyoxyethylene sorbitol monostearate,polyoxyethylene sorbitol mono-oleate, and polyethylene glycolmonooleate. Rust inhibitors or anticorrosion agents may also be othercompounds, which include, for example, stearic acid and other fattyacids, dicarboxylic acids, metal soaps, fatty acid amine salts, metalsalts of heavy sulfonic acid, partial carboxylic acid ester ofpolyhydric alcohols, and phosphoric esters. In another embodiment, therust inhibitor is a calcium stearate salt.

Detergents: In engine oil compositions, metal-containing or ash-formingdetergents function both as detergents to reduce or remove deposits andas acid neutralizers or rust inhibitors, thereby reducing wear andcorrosion and extending engine life. Detergents generally comprise apolar head with long hydrophobic tail, with the polar head comprising ametal salt of an acid organic compound.

In one embodiment, the engine oil composition contains one or moredetergents, which are normally salts, e.g., overbased salts. Overbasedsalts, or overbased materials, are single phase, homogeneous Newtoniansystems characterized by a metal content in excess of that which wouldbe present according to the stoichiometry of the metal and theparticular acidic organic compound reacted with the metal. In anotherembodiment, the engine oil composition comprises at least a carboxylatedetergent. Carboxylate detergents, e.g., salicylates, can be prepared byreacting an aromatic carboxylic acid with an appropriate metal compoundsuch as an oxide or hydroxide. In yet another embodiment, the engine oilcomposition comprises at least an overbased detergent. Examples of theoverbased detergents include, but are not limited to calcium sulfonates,calcium phenates, calcium salicylates, calcium stearates and mixturesthereof. Overbased detergents may be low overbased (e.g., Total BaseNumber (TBN) below about 50). Sutiable overbased detergents mayalternatively be high overbased (e.g., TBN above about 150) or mediumoverbased (e.g., TBN between 50 and 150). The lubricating oilcompositions may comprise more than one overbased detergents, which maybe all low-TBN detergents, all high-TBN detergents, or a mix of thosetwo types. Other suitable detergents for the lubricating oilcompositions include “hybrid” detergents such as, for example,phenate/salicylates, sulfonate/phenates, sulfonate/salicylates,sulfonates/phenates/salicylates, and the like. In other embodiments, thecomposition comprises detergents made from alkyl benzene and fumingsulfonic acid, phenates (high overbased, medium overbased, or lowoverbased), high overbased phenate stearates, phenolates, salicylates,phosphonates, thiophosphonates, sulfonates, carboxylates, ionicsurfactants and sulfonates and the like.

Oxidation Inhibitors/Antioxidants: Oxidation inhibitors or antioxidantsreduce the tendency of mineral oils to deteriorate in service, whichdeterioration is evidenced by the products of oxidation such as sludge,lacquer, and varnish-like deposits on metal surfaces. In one embodiment,the engine oil composition contains from about 50 ppm to about 5.00 wt.% of at least an antioxidant selected from the group of phenolicantioxidants, aminic antioxidants, or a combination thereof. In otherembodiments, the amount of antioxidants is between 0.10 to 3.00 wt. %.In yet other embodiments, ranging from about 0.20 to 0.80 wt. %. Anexample of an antioxidant used is di-C₈-diphenylamine, in an amount ofabout 0.05 to 2.00 wt. % of the total weight of the oil composition.Other examples of antioxidants include MoS and Mo oxide compounds.

In one embodiment, the antioxidant is selected from the group ofhindered phenols; alkaline earth metal salts of alkylphenolthioestershaving C₅ to C₁₂ alkyl side chains; calcium nonylphenol sulphide; oilsoluble phenates and sulfurized phenates; phosphosulfurized orsulfurized hydrocarbons or esters; phosphorous esters; metalthiocarbamates; oil soluble copper compounds known in the art; phenylnaphthyl amines such as phenylene diamine, phenothiazine, diphenylamine, diarylamine; phenyl-alphanaphthylamine, 2,2′-diethyl-4,4′-dioctyldiphenylamine, 2,2′diethyl-4-t-octyldiphenylamine; alkaline earth metalsalts of alkylphenol thioesters, having C₅ to C₁₂ alkyl side chains,e.g., calcium nonylphenol sulfide, barium t-octylphenol sulfide, zincdialkylditbiophosphates, dioctylphenylamine, phenylalphanaphthylamineand mixtures thereof. Some of these antioxidants further function ascorrosion inhibitors. Other suitable antioxidants which also function asantiwear agents include bis alkyl dithiothiadiazoles such as2,5-bis-octyl dithiothiadiazole.

Anti-foamants: In one embodiment, the engine oil further comprises ananti-foamant (foam inhibitor) in amounts ranging from about 5 to about50 ppm. Examples include alkyl methacrylate polymers, dimethyl siliconepolymers, and foam inhibitors of the polysiloxane type, e.g., siliconeoil and polydimethyl siloxane, for foam control. In another embodiment,the anti-foamant is a mixture of polydimethyl siloxane andfluorosilicone. In yet another embodiment, the engine oil furthercomprises an acrylate polymer anti-foamant, with a weight ratio of thefluorosilicone antifoamant to the acrylate anti-foamant ranging fromabout 3:1 to about 1:4. In a fourth embodiment, the engine oil comprisesan anti-foam-effective amount of a silicon-containing anti-foamant suchthat the total amount of silicon in the engine oil is at least 30 ppm.In yet another embodiment, the silicon-containing antifoam agent isselected from the group consisting of fluorosilicones,polydimethylsiloxane, phenyl-methyl polysiloxane, linear siloxanes,cyclic siloxanes, branched siloxanes, silicone polymers and copolymers,organo-silicone copolymers, and mixtures thereof.

Anti-wear agents: Anti-wear agents can also be added to the engine oilcomposition. In one embodiment, the composition further comprises atleast an anti-wear agent selected from phosphates, phosphites,carbamates, esters, sulfur containing compounds, and molybdenumcomplexes. Other representative of suitable antiwear agents are zincdialkyldithiophosphate, zinc diaryldilhiophosphate, Zn or Modithiocarbamates, phosphites, amine phosphates, borated succinimide,magnesium sulfonate, and mixtures thereof. In one embodiment, thecomposition further comprises at least a dihydrocarbyl dithiophosphatemetal as antiwear and antioxidant agent in amounts of about 0.1 to about10 wt. %, The metal may be an alkali or alkaline earth metal, oraluminum, lead, tin, molybdenum, manganese, nickel or copper.

Extreme Pressure Agents: In one embodiment, the engine oil compositionfurther comprises an extreme pressure agent. Examples include alkalineearth metal borated extreme pressure agents and alkali metal boratedextreme pressure agents. Other examples include sulfurized olefins, zincdialky-1-dithiophosphate (primary alkyl, secondary alkyl, and aryltype), di-phenyl sulfide, methyl tri-chlorostearate, chlorinatednaphthalene, fluoroalkylpolysiloxane, lead naphthenate, neutralized orpartially neutralized phosphates, di-thiophosphates, and sulfur-freephosphates.

Some of the above-mentioned additives can provide a multiplicity ofeffects; thus for example, a single additive may act as a dispersant aswell as an oxidation inhibitor. These multifunctional additives are wellknown. In one embodiment, when the engine oil composition contains oneor more of the above-mentioned additives, each additive is typicallyblended into the base oil in an amount that enables the additive toprovide its desired function. It may be desirable, although notessential, to prepare one or more additive concentrates comprisingadditives (concentrates sometimes being referred to as “additivepackages”) whereby several additives can be added simultaneously to theoil to form the end oil composition. The final composition may employfrom about 0.5 to about 30 wt. % of the concentrate, the remainder beingthe oil of lubricating viscosity. The components can be blended in anyorder and can be blended as combinations of components.

Method for Making: The Pour Point Reducing Blend Component and otheradditives can be blended into the base oil matrix individually or invarious sub-combinations. In one embodiment, all of the components areblended concurrently as an additive concentrate, or additives plus adiluent, such as a hydrocarbon solvent. The use of an additiveconcentrate takes advantage of the mutual compatibility afforded by thecombination of ingredients when in the form of an additive concentrate.In another embodiment, the engine oil composition is prepared by mixingthe base oil and the pour point depressant with the separate additivesor additive package(s) at an appropriate temperature, e.g., 60° C.,until homogeneous.

Applications: Among other things, the engine oil composition resistsviscosity shear and is formulated with a lower level of viscositymodifiers for excellent protection of gears, bearings, cam lobes, camfollowers, and other high-pressure components in engines andtransmissions.

The composition delivers lubrication in all types of automotive andcommercial vehicles gasoline and diesel engines, gasoline fueledfour-stroke outboard, inboard, inboard/outboard (lPO) and personalwatercraft motors, including but not limited to large and small gasolineor diesel engines in cars, motorcycles, trucks, motor homes, maintenanceequipment, heavy equipment, street rods, military, and marineapplications.

Properties: In one embodiment, the engine oil composition ischaracterized as meeting at least one of International LubricantStandardization and Approval Committee (ILSAC) GF-4, American PetroleumInstitute (API) CI-4, API CJ4 performance specifications. In oneembodiment, the engine oil composition meets both ILSAC GF-4 and APICI-4 specifications. In another embodiment, the engine oil compositionmeets or exceeds European ACEA: A1, A5, B1, B5, ACEA C1, ACEA C2, ACEAC3, ACEA C4A, and JASO DL-1, and all ILSAC GF-4 for API CertifiedGasoline Engine Oils and meets Energy Conserving Standards. In yetanother embodiment, the engine oil composition meets the specificationsfor SAE J300 viscosity grade 0W-XX, 5W-XX, 10W-XX, 15W-XX, 20W-XX, or25W-XX engine oil, wherein XX represents the integer 20, 30, 40, 50 or60.

In one embodiment, the engine oil composition is characterized asmeeting the requirements of SAE J300 over a wide temperature range whilestill having a low level of viscosity modifiers (viscosity indeximprovers or VII). Depending on the diluted factor of the viscositymodifiers used, this amount may range from 0.3 to 25 wt. %. In oneembodiment, the reduced amount of viscosity modifiers is less than 10wt. %.

In one embodiment, the engine oil composition has a kinematic viscosityat 100° C. as specified according to SAE J300 for the applicable grade.In one embodiment, the composition has a kinematic viscosity at 100° C.between 3.5 and 25 mm²/s. In a second embodiment, a kinematic viscosityat 100° C. between 8 and 20 mm²/s.

Viscometrics is an important lubricant parameter that governs thesuccessful operation of engine oils. In one embodiment, the engine oilcomposition comprising a isomerized base oil has an apparent viscosityof 60,000 cP or less in MRV test (ASTM D4684-07@−40° C.).

In one embodiment, the engine oil composition has a cold crank simulatorviscosity at −35° C. of less than 9000 cP, and less than 7500 cP in asecond embodiment, and less than 6000 cP in a third embodiment. In oneembodiment, the engine oil composition has a mini rotary viscosity at−30° C. of less than 60000 cP and a yield stress of less than 35 Pa (asmeasured per ASTM D4684-07@−30° C.).

In one embodiment, the engine oil composition is characterized asexhibiting excellent fuel economy performance, of at least 1% comparedto an engine oil composition of the prior art, i.e., engine oilcompositions employing non-isomerized base oils. Fuel economyperformance can be measured using the Phase I Sequence VIB ScreenerTest, to be described in the Examples section. In another embodiment,the fuel savings is at least 1.5% compared to engine oil compositions ofthe prior art. In a third embodiment, the fuel savings is at least1.75%.

EXAMPLES

The examples are given as non-limitative illustration of aspects of theinvention. The compositions were subject to a number of tests includingthe following non-standard tests:

Phase I Sequence VIB Screener Test: This is an abbreviated test methodof ASTM D6837-06 for measurement of effects of automotive engine oils onfuel economy. ASTM D6837-06, Standard Test Method for Measurement ofEffects of Automotive Engine Oils on Fuel Economy of Passenger Cars andLight-Duty Trucks in Sequence VIB Spark Ignition Engine, is an enginedynamometer test that measures the ability of a lubricant to improve thefuel economy of passenger cars and light-duty trucks equipped with a lowfriction engine. In the abbreviated test, testing ends after Phase I anddoes not proceed to Phase II. As a result, the method by which % fueleconomy improvement (FEI) is calculated is also slightly different.

Under ASTM D6837-06, % fuel economy improvement (FEI) is calculatedusing weighted results from two baseline calibration (BC) candidates,one before Phase I and one after Phase II. In the abbreviated test usedherein, 100% of a single baseline candidate is used in making the % FEIcalculation as described on page 9 of ASTM D6837-06, with higher % FEIvalues indicating improved fuel economy. Fuel economy improvement (FEI)at Stage-1,-2 and -3 depends on a friction modifier in the lubricant andFEI at Stage-4 and Stage-5 depends on viscometric properties of thelubricant.

The calculation of % FEI for each stage is as follows. First, the brakespecific fuel consumption (BSFC) in kg/kW,h for each stage is calculatedby the following formula: (Integrated Fuel Flow)×(9549.3)/BSFC(Integrated Load) (Integrated Speed). The BSFC data for each stage ismultiplied by the nominal power and by the weight factor to arrive at kgof weighted fuel consumed for each stage. Based on total fuel consumedat Phase I (from stage 1 to 5), % FEI for each stage can be calculatedas follows: ((Weighted fuel consumed for each stage in the BC before oil)−(Weighted fuel consumed for each stage in the test oil))/(total fuelconsumed at Phase I by BC before oil)×100.

In the Phase I Sequence VIB Screener Test used herein, Stage-4 andStage-5 of are run at more hydrodynamic lubricating conditions (i.e.,thicker oil film), while Stage-1 and Stage-2 are run closer to boundarylubricating conditions. Under boundary conditions, fuel economy is moredependent on added friction modifiers, which is not as important forfuel economy under more hydrodynamic lubricating conditions.

Traction Coefficient Test Method: As engine oils with lower tractioncoefficients are desirable as they provide improved fuel economy, someof the examples were subject to the Traction Coefficient Test Method asdescribed in US Patent Publication No. 20050241990. In this test,Traction data are obtained with an MTM Traction Measurement System fromPCS Instruments, Ltd. The unit is configured with a polished 19 mmdiameter ball (SAE AISI 52100 steel) angled at 220 to a flat 46 mmdiameter polished disk (SAE AISI 52100 steel). Measurements are made at40° C., 70° C., 100° C., and 120° C. The steel ball and disk are drivenindependently by two motors at an average rolling speed of 3 Meters/secand a slide to roll ratio (SRR) of 40% [defined as the difference insliding speed between the ball and disk divided by the mean speed of theball and disk. SRR=(Speed1−Speed2)/((Speed1+Speed2)−/2)]. The load onthe ball/disk is 20 Newton resulting in an estimated average contactstress of 0.546 GPa and a maximum contact stress of 0.819.

EXAMPLES

Two runs with Group-III based engine lubricating oil and three runs withFischer-Tropsch derived base oil based engine lubricating oil wereconducted. In the examples, viscosity at 100° C., High-TemperatureHigh-Shear (HTHS) viscosity at 150° C., and Noack volatility wereadjusted to the same level to eliminate any influence from theseproperties in the results. All oils were blended as SAE OW-20 to thesame Blend Viscosity of 4.3 mm²/s at 100° C.

Unless specified otherwise, the components in the examples are asfollows (and expressed as wt. % in the Tables) with the sameadditives/additive package being used for the examples.

FTBO base oils: are from Chevron Corporation of San Ramon, Calif. Theproperties of the FTBO base oils used in the examples are shown in Table4. The oils have very low initial boiling points, excellent volatility,high Oxidator BN values, high total weight % molecules withcycloparaffinic functionality, and high ratios of mono- tomulti-cycloparaffins.

Group III base stock: a commercially available base stock having akinematic viscosity at 100° C. of 4.307 and a CCS VIS at −35° C. of 3165mPa·s.

VII is a commercially available viscosity index improver.

PPD is a commercially available pour point depressant.

FM is a commercially available friction modifier.

Additive Package is a commercially available additive package.

Examples 1-2

An embodiment of an engine oil composition containing an isomerized baseoil blend was compared with a formulation containing a group III baseoil of the prior art. The results are shown in Table 1.

TABLE 1 Example 1 Comparative Example 2 SAE Grade 0W-20 0W-20 Group-IIIBase Stock, wt % 81.34 — Base Oil 1, wt % — 47.18 Base Oil 2, wt % —31.46 Additive Package, wt % 10.89 10.89 FM, wt % 1.17 1.17 VII, wt %6.30 9.00 PPD, wt % 0.30 0.30 Viscosity @ 100° C. (ASTM 8.35 8.55 D445),mm²/s VI (ASTM D2270), mm²/s 167 193 CCS @ −35° C. (ASTM D5293), 54902150 mPa HTHS @ 150° C. (ASTM 4683), 2.63 2.66 mPa Blend Viscosity(KV100, 4.288 3.748 Calculated), mm²/s Blend Viscosity (KV40, 19.9014.87 Calculated), mm²/s MRV @ −40° C. (ASTM D4684), 20000 7330 mPaYield Stress No No Noack Volatility, % 13.6 14.8 Phase I Sequence VIBScreener Test Results Phase I FEI at each stage Stage-1, % 0.38 0.370.46 0.39 0.37 Stage-2, % 0.20 0.18 0.16 0.19 0.22 Stage-3, % 0.25 0.260.38 0.26 0.27 Stage-4, % 0.72 0.81 1.01 0.87 0.86 Stage-5, % 0.66 0.730.80 0.77 0.77 Phase I Total FEI, % 2.20 2.34 2.81 2.48 2.50 Phase IStage-1 + Stage-2 + 0.82 0.80 1.00 0.84 0.87 Stage-3 FEI, % Phase IStage-4 + Stage-5 FEI, % 1.38 1.54 1.81 1.64 1.63

As shown, the engine lubricating oil containing isomerized base oil(s)of Example 2 produces significantly higher fuel economy improvement(FEI), especially in hydrodynamic lubrication condition compared to theGroup-III based engine lubricating oils (Example 1), with astatistically significant p-value of Phase I Stage-4+Stage-5 FEI of0.044. A p-value close to 0 means the data, with respect to the specifictest, are not the same. A p-value <0.05 means the data are statisticallydifferent, based on a 95^(th) percentile confidence interval criteria.

Additionally, total Phase-I FEI in Example 2 was also significantlyhigher than that of the prior art engine oil (statistically significantp-value of the Phase-I total FEI of 0.041). Without wishing to be boundby theory, it is believed that the slightly lower base oil BlendViscosity of Example 2 (containing isomerized base oils), as compared tothe Group-III engine oil of the prior art, may have contributed to theespecially good Phase I Stage-4+Stage-5% FEI.

Examples 3-6

In these examples, friction modifiers were omitted from theformulations. The results are as indicated in Table 2.

TABLE 2 Example 4 Example 6 Example 3 Comparative Example 5 ComparativeSAE Grade 0W-20 0W-20 0W-20 0W-20 Group-III Base Stock, wt % — 84.21 —83.89 Base Oil 3, wt % 76.18 — 75.79 — Base Oil 4, wt % 7.53 — 7.50 —Additive Package, wt % 8.39 8.39 8.71 8.71 FM x x ✓ ✓ VII, wt % 7.607.10 7.70 7.10 PPD, wt % 0.3 0.3 0.3 0.3 Viscosity @ 100° C. 8.43 8.468.54 8.50 (ASTM D445), mm²/s Viscosity @ 40° C. (ASTM 42.30 45.45 43.0445.26 D445), mm²/s VI (ASTM D2270), mm²/s 181 165 177 168 CCS @ −35° C.(ASTM 3010 5240 3050 5390 D5293), mPa HTHS @ 150° C. (ASTM 2.58 2.602.60 2.60 4683), mPa Blend Viscosity (KV100, 4.313 4.307 4.313 4.307Calculated), mm²/s Blend Viscosity (KV40, 18.91 20.13 18.91 20.13Calculated), mm²/s MRV @ −40° C. (ASTM 8200 22400 8800 28900 D4684), mPaYield Stress No No No No Noack Volatility, % 18.91 20.13 18.91 20.13Phase I Sequence VIB Screener Test Results Phase I Total FEI, % 1.601.78 1.76 1.58 1.96 2.11 1.98 1.84 Phase I Stage-1 + Stage-2 + 0.20 0.460.53 0.31 0.67 0.80 0.75 0.62 Stage-3 FEI, % Phase I Stage-4 + Stage-51.39 1.33 1.24 1.26 1.29 1.31 1.23 1.22 FEI, %

As shown in Table 2 above, Examples 3 and 5 with compositions containingisomerized base oil(s) show fuel economy benefits relative to the priorart engine oil in Stage-4+Stage-5 of Phase I Sequence VIB ScreenerTests, regardless of whether or not a friction modifier (FM) wasincluded. With respect to these Stage-4+Stage-5 results, the differencewas statistically significant both when FM was included (p-value=0.036)and when FM was not included (p-value=0.046). Additionally through thePhase I Sequence VIB Screener Test, engine oil compositions containingisomerized base oil(s) show fuel economy improvements compared to theconventional Group III based engine oils.

Examples 7-10

Engine oil compositions with and without the addition of frictionmodifier(s) according to Table 3 were formulated and subject to theTraction Coefficient Test Method.

TABLE 3 Example 8 Example 10 Example 7 Comparative Example 9 ComparativeSAE Grade 0W-20 0W-20 0W-20 0W-20 Group-III Base — 81.34 — 83.46 Stock,wt % Base Oil 1, wt % 47.18 — 48.73 — Base Oil 2, wt % 31.46 — 32.48 —Additive Package, 10.89 10.89 9.49 9.49 wt % FM 1.17 1.17 — — VII, wt %9.00 6.30 9.00 6.75 PPD, wt % 0.30 0.30 0.30 0.30

Results of tests according to the Traction Coefficient Test Method arepresented in FIGS. 1-4. FIG. 1 compares the Traction Coefficient versusDisk Speed of Example 7 (with isomerized base oils) and ComparativeExample 8 with a prior art formulation, with both formulations includinga friction modifier. FIG. 3 is a graph of log₁₀ Traction Coefficientversus Disk Speed at various slide to roll ratio (SRR) values forExamples 7 and 8.

For formulations without the addition of friction modifiers, FIG. 2compares the Traction Coefficient versus Disk Speed of Example 9(containing isomerized base oils) with Comparative Example 10, an engineoil with Group III base stock. FIG. 4 is a graph of log₁₀ TractionCoefficient versus Disk Speed at various SRR values for Examples 9 and10. As shown in the figures, engine oil compositions comprisingisomerized base oils demonstrate lower traction coefficients, and thusimproved economy.

The properties of the isomerized base oils used in the examples arepresented in Table 4.

TABLE 4 Base Oil 1 Base Oil 2 Base Oil 3 Base Oil 4 Kinematic Viscosity@ 40° C., mm²/s 17.74 37.92 Kinematic Viscosity @ 100° C., mm²/s 3.5624.039 4.12 7.129 Viscosity Index 146 150 138 153 Cold Crank Viscosity @−40° C., mPa 1,700 2,450 Cold Crank Viscosity @ −35° C., mPa 1,167 1,3351596 6966 Pour Point, ° C. −27 −25 −27 −20 Oxidator BN, hrs 37.64 50.4341.02 42.07 Noack Volatility, wt % 18.69 13.01 10.22 2.49 Wt % Aromaticsby HPLC-UV 0.0353 0.0202 <0.001. <0.001 SIMDIST TBP (wt %), ° F.  0.5327 418 732 805  5 609 723 758 836 10 733 741 770 850 20 760 763 784 86930 776 780 795 884 40 789 796 805 897 50 801 812 813 913 60 814 829 822930 70 826 847 832 947 80 840 867 843 973 90 855 887 857 1004 95 866 899867 1033 99.5 893 921 887 1078 T₉₅-T₅ Boiling Range Distribution, ° F.257 (143) 176 (98) 109 (61) 197 (109) (° C.) FIMS Alkanes 81.1 78.9 75.373.1 1-Unsaturation 17.9 20.3 23.6 26.5 2-Unsaturation 0.8 0.8 0.9 0.23-Unsaturation 0.1 0 0.1 0 4-Unsaturation 0 0 0 0 5-Unsaturation 0 0 0 06-Unsaturation 0.1 0 0.1 0.2 % Olefins by Proton NMR 0.00 0.00 0.32 1.38Wt % Molecules with 17.9 20.3 23.3 25.1 MonocycloparaffinicFunctionality Wt % Molecules with 1.0 0.8 1.1 0.4 MulticycloparaffinicFunctionality Mono/Multi ratio 18.6 26.0 21.2 62.8 Alkyl Branches/100Carbons 9.20 9.58 9.42 8.63

For the purpose of this specification and appended claims, unlessotherwise indicated, all numbers expressing quantities, percentages orproportions, and other numerical values used in the specification andclaims, are to be understood as being modified in all instances by theterm “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in the following specification andattached claims are approximations that may vary depending upon thedesired properties sought to be obtained and/or the precision of aninstrument for measuring the value, thus including the standarddeviation of error for the device or method being employed to determinethe value. The use of the term “or” in the claims is used to mean“and/or” unless explicitly indicated to refer to alternatives only orthe alternative are mutually exclusive, although the disclosure supportsa definition that refers to only alternatives and “and/or.” The use ofthe word “a” or “an” when used in conjunction with the term “comprising”in the claims and/or the specification may mean “one,” but it is alsoconsistent with the meaning of “one or more,” “at least one,” and “oneor more than one.” Furthermore, all ranges disclosed herein areinclusive of the endpoints and are independently combinable. In general,unless otherwise indicated, singular elements may be in the plural andvice versa with no loss of generality. As used herein, the term“include” and its grammatical variants are intended to be non-limiting,such that recitation of items in a list is not to the exclusion of otherlike items that can be substituted or added to the listed items.

It is contemplated that any aspect of the invention discussed in thecontext of one embodiment of the invention may be implemented or appliedwith respect to any other embodiment of the invention. Likewise, anycomposition of the invention may be the result or may be used in anymethod or process of the invention.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to make and use the invention. The patentable scope is defined bythe claims, and may include other examples that occur to those skilledin the art. Such other examples are intended to be within the scope ofthe claims if they have structural elements that do not differ from theliteral language of the claims, or if they include equivalent structuralelements with insubstantial differences from the literal languages ofthe claims. All citations referred herein are expressly incorporatedherein by reference.

1. An engine oil composition meeting at least one of ILSAC GF-4, APICI-4, API CJ4, ACEA A1, ACEA A5, ACEA B1, ACEA B5, ACEA C1, ACEA C2,ACEA C3, ACEA C4A, and JASO DL-1 performance specifications, thecomposition comprising: at least an isomerized base oil comprising aconsecutive number of carbon atoms and having a CCS Viscosity at −35° C.of less than or equal to 7000 mPa, a T₉₅-T₅ boiling range distributionof less than or equal to 200° C., a ratio of weight percent moleculeswith monocycloparaffinic functionality to weight percent molecules withmulticycloparaffinic functionality of greater than 15, and an OxidatorBN of greater than 30 hours; and 0.05 to 40 wt %. of at least anadditive selected from the group of metal detergents, dispersants, wearinhibitors, anti-oxidants, friction modifiers, viscosity modifiers,corrosion inhibitors, seal swelling agents, metal deactivators,anti-foamants, and mixtures thereof.
 2. The engine oil composition ofclaim 1, wherein the composition meets ILSAC GF-4 performancespecification.
 3. The engine oil composition of claim 1, where thecomposition contains less than 0.3 wt. % of a friction modifier.
 4. Theengine oil composition of claim 2, wherein the composition meets ILSACGF-4 performance specification and wherein the composition does notcontain any added friction modifier.
 5. The engine oil composition ofclaim 1, wherein the composition exhibits a fuel economy improvement ofgreater than or equal to 1% compared to an engine oil compositionemploying a non-isomerized base oil, wherein the fuel economyimprovement is measured by summing Stage-4 and Stage-5 Phase I SequenceVIB Screener Test results.
 6. The engine oil composition of claim 5,wherein the fuel economy improvement of greater than or equal to 1.5%.7. The engine oil composition of claim 6, wherein the fuel economyimprovement of greater than or equal to 1.75%.
 8. The engine oilcomposition of claim 1, wherein the isomerized base oil has an OxidatorBN of at least 35 hours.
 9. The engine oil composition of claim 1,wherein the isomerized base oil has an Oxidator BN of at least 50 hours.10. The engine oil composition of claim 1, wherein the isomerized baseoil has a viscosity index of at least
 135. 11. The engine oilcomposition of claim 10, wherein the isomerized base oil has a viscosityindex of at least
 140. 12. The engine oil composition of claim 1,wherein the isomerized base oil is a Fischer-Tropsch derived base oilmade from a waxy feed.
 13. The engine oil composition of claim 1,wherein isomerized base oil has an average degree of branching in themolecules between 6.5 and 10 alkyl branches per 100 carbon atoms. 14.The engine oil composition of claim 1, wherein the isomerized base oilhas a wt % Noack volatility between 0 and
 100. 15. The engine oilcomposition of claim 1, wherein the isomerized base oil has anauto-ignition temperature (AIT) greater than an amount defined by:1.6×(Kinematic Viscosity at 40° C., in mm²/s)+300.
 16. The engine oilcomposition of claim 1, wherein the isomerized base oil has a totalweight percent of molecules with cycloparaffinic functionality ofgreater than
 10. 17. The engine oil composition of claim 14, wherein theisomerized base oil is made from a process in which the highlyparaffinic wax is hydroisomerized using a shape selective intermediatepore size molecular sieve comprising a noble metal hydrogenationcomponent, and under conditions of about 600° F. to 750° F. and whereinthe isomerized base oil has a Noack volatility of less than 50 weight %.18. The engine oil composition of claim 14, wherein the isomerized baseoil comprises greater than 3 weight % molecules with cycloparaffinicfunctionality and less than 0.30 weight percent aromatics.
 19. Theengine oil composition of claim 14, wherein the isomerized base oil hasa traction coefficient of less than 0.023 when measured at a kinematicviscosity of 15 mm²/s and at a slide to roll ratio of 40%.
 20. Theengine oil composition of claim 1, wherein the engine oil compositionexhibits an MRV of less than or equal to 12,000 mPa at −40° C.
 21. Theengine oil composition of claim 20, wherein the engine oil compositionexhibits an MRV of less than or equal to 8,800 mPa at −40° C.
 22. Theengine oil composition of claim 21, wherein the engine oil compositionexhibits an MRV of less than or equal to 7,330 mPa at −40° C.
 23. Theengine oil composition of claim 1, wherein the engine oil compositionexhibits a CCS Viscosity at −35° C. of less than or equal to 1400 mPa.24. The engine oil composition of claim 22, wherein the engine oilcomposition exhibits a CCS Viscosity at −35° C. of less than or equal to1200 mPa.